Piperidylidene derivatives of carboxy-5H-dibenzo[a,d]cycloheptene

ABSTRACT

The new 1-alkyl-4-(1, 2, or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine compounds are prepared from the corresponding 1, 2 or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-one by reaction with a Grignard reagent prepared from a 1-alkyl-4-halo piperidine to form an intermediate carbinol, or a 1, 2 or 3-carboxy-5-(1-alkyl-4-piperidyl)-5H-dibenzo[a,d]cyclohepten-5-ol which is then dehydrated to produce the desired 1-alkyl-4-(1, 2 or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, or alternatively by hydrolysis of a 1-alkyl-4-(1, 2 or 3-cyano-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine compound to form the corresponding 1-alkyl-4-(1, 2 or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine compound.

This is a continuation-in-part of copending U.S. Ser. No. 280,685, filed Aug. 14, 1972, now U.S. Pat. No. 3,960,872 which application is a continuation of U.S. Ser. No. 9049, filed Feb. 5, 1970 and now abandoned, which in turn is a continuation-in-part of U.S. Ser. No. 4123, filed Jan. 19, 1970, and now abandoned.

SUMMARY

This invention concerns 1-alkyl-4-(1, 2 or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine compounds, acid addition salts thereof, and processes for the preparation of said compounds. It also concerns pharmaceutical compositions in which said 1, 2 or 3-carboxy compounds are incorporated as the active medicinal agent. The compounds of the present invention are also useful as intermediates in the preparation of the corresponding 10-oxo or hydroxy compounds.

BACKGROUND

Allergic conditions in the past have been treated with a variety of drugs including those characterized as 1-alkyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidines.

Prior to the present invention, it was known that the compound cyproheptadiene of the structure ##SPC1##

Was an active antihistaminic and antiserotonin agent and was therefore useful in the treatment or relief of certain allergic conditions. This is disclosed in U.S. Pat. No. 3,014,911, Edward L. Engelhardt, which patent was issued Dec. 26, 1961.

The novel 1, 2 or 3-carboxy compounds of the present invention are distinguished from the prior art patented compounds by their ability to stimulate appetite in underweight or undernourished patients without the concommitant side effects present in other cyproheptadine analogs, such as anti-cholinergic activity. In standard laboratory animals, the compounds of the present invention are found to have appetite stimulant activity.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to derivatives of 1-alkyl-4-(1, 2 or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidines which are useful as drugs for the stimulation of appetite in underweight or undernourished human patients. The compounds of the present invention are at the same time relatively free of ancillary pharmacological actions, other than antihistaminic activity, associated with such compounds. The ancillary pharmacological actions are present, if at all, at a substantially low level compared to cyproheptadine. In particular, the present invention relates to derivatives of the following structure: ##SPC2##

wherein

R₂ is loweralkyl or loweralkenyl, preferably containing from 1 tp 6 carbon atoms;

R is methyl or ethyl and may replace one or more of the hydrogens in positions 2, 3, 5 or 6 of the piperidine ring, provided that only one of positions 3 or 5 is monosubstituted at one time;

n is 1 or 2;

X is carboxy; and

X' is selected from hydrogen and an alkyl group having up to 6 carbon atoms.

The invention also includes salts of the above compounds such as acid addition salts which may interchangeably be used in therapeutic applications with the base and likewise includes N-oxide derivatives thereof.

The invention also includes the administration of 1-alkyl-4-(1, 2, or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine or an acid addition salt thereof as an appetite stimulant in the treatment of symptoms of anorexia or malnutrition in human patients. The treatment involves preferably the oral administration of an effective amount of the selected 1-alkyl-4-(1, 2, or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine at a dosage level which will afford relief from the aforementioned conditions.

The compounds of the present invention may be administered to persons in any of the usual pharmaceutical oral forms such as tablets, elixirs and aqueous suspensions, e.g., the active ingredient and a pharmaceutical carrier, in an amount from 0.10 up to 50 mgs. per dose given 2 to 4 times daily. Sterile solutions for injection containing from 0.001 to about 25 mgs. per dose are injected 2 to 4 times daily. Further, the compounds of this invention are ordinarily easily administered as a salt and any convenient non-toxic addition salt formed in a conventional manner may be employed. As examples of the salts convenient for use are salts of the compounds of the present invention with hydrochloric acid, sulfuric acid, phosphoric acid, acetic acid, propionic acid, citric acid, tartaric acid, succinic acid, maleic acid and the like. These salts are generally equivalent in potency to the bases from which they are formed taking into consideration the stoichiometric quantities employed.

The compounds of the present invention are conveniently prepared from the compounds disclosed in the Engelhardt patent U.S. Pat. No. 3,014,911, or from appropriately substituted 5H-dibenzo[a,d]cycloheptenones, in the manner described in Column 3 of that patent, the 5H-dibenzo[a,d]cyclohepten-5-one or a derivative containing an X and/or X' substituent in the benzene rings being treated with a Grignard reagent prepared from a 1-alkyl-4-halo piperidine or a ring alkylated 1-alkyl-4-halo piperidine to form an intermediate carbinol, a 5-(1-alkyl-4-piperidyl)-5H-dibenzo[a,d]cyclohepten-5-ol which is then dehydrated to produce the desired 1-alkyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, e.g., a 1-alkyl-4-(1, 2, or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine.

In an alternate method of preparation of the compounds of the present invention, a 1, 2 or 3-bromo-5H-dibenzo[a,d]cyclohepten-5-ylidene piperidine of the formula ##SPC3##

is treated with a metal cyanide, preferably cuprous cyanide, in an inert liquid reaction medium at an elevated temperature to produce the corresponding compound of the following formula, wherein the bromo substituent has been replaced by a cyano substituent: ##SPC4##

wherein R, R₂, X' and n are as defined on Page 4 hereinabove. The resulting cyano derivative is hydrolyzed to form the corresponding carboxy derivative.

A still further alternate method of preparing the compounds of the present invention employs a combination of the methods described hereinabove. The bromo-substituted dibenzocycloheptenone, i.e., the 1, 2 or 3-bromo-5H-dibenzo[a,d]cyclohepten-5-one, is treated with cuprous cyanide to effect replacement of the bromo substituent and produce the corresponding 1, 2 or 3-cyano-5H-dibenzo[a,d]cyclohepten-5-one. The thus-formed cyano ketone is then treated with a Grignard reagent prepared from a 1-alkyl-4-halopiperidine to form an intermediate carbinol, a 1, 2 or 3-cyano-5-(1-alkyl-4-piperidyl)-5H-dibenzo[a,d]cyclohepten-5-ol which is then heated with aqueous acid to effect dehydration of the carbinol and hydrolysis of the nitrile substituent with resultant production of the desired 1-methyl-4-(1, 2 or 3-carboxy-5H-dibenzo[a,d]-cyclohepten-5-ylidene)-piperidine.

The compounds of this invention, in addition to their activity as appetite stimulants, are useful as intermediates or starting materials in the process of preparing appropriately substituted 1-alkyl-4-(1, 2 or 3-carboxy-5H-dibenzo[a,d]cycloheptene)-piperidine having a 10 or 11-keto or 10 or 11-hydroxy substituent as hereinafter described.

The process for using the compounds of the present invention in the preparation of other biologically active compounds is conveniently illustrated by the following process outline: ##SPC5##

wherein

R₂ is hydrogen, loweralkyl or lower alkenyl, preferably containing from 1 to 6 carbon atoms;

R is methyl or ethyl and may replace one or more of the hydrogens in positions 2, 3, 5 or 6 of the piperidine ring, provided that only one of positions 3 or 5 is monosubstituted at one time;

wherein

n is 1 or 2; and

X' is selected from hydrogen and an alkyl group having up to 6 carbon atoms.

The process outlined in the above flowsheet is a method of introducing a 10 or 11-oxygen substituent into Compound A, i.e., 1-alkyl-1, 2 or 3-carboxy-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine by the process of bromination, dehydrobromination, enamine formation and hydrolysis. This process is also applicable to the derivatives indicated in which the benzene rings are substituted by one or more of the named substituents.

In the conversion of Compound B to Compound C wherein the starting compound is unsymmetrically substituted, e.g., X' is other than a carboxy group, the product produced is a mixture of position isomers which differ in that the bromine substituent is present at either the 10- or 11- positions. This mixture is separated by conventional methods such as chromatography and crystallization to produce the respective 10-bromo or 11-bromo position isomers of Compound C. Each of these isomers, but preferably the mixture without further crystallization, is converted to the corresponding Compound D. This reaction is conducted by treatment of the mono-bromo derivative C with a strong base in the presence of piperidine to form the corresponding enamine Compound D. In this instance, as in the formation of the mono-bromo compound, the reaction gives rise in the case of the unsymmetrically substituted compounds to position isomers in which the N-piperidyl substituent in the isomer is present either in the 10- or 11- position. These position isomers are separated by conventional means such as by chromatography and or crystallization. Preferably, the mixture of isomers, but alternatively either of the position isomers, is the converted to the corresponding 10-keto, 11-keto, or a mixture of the two isomeric compounds. This mixture of 10- and 11- keto compounds is also readily separated into the component isomers by conventional techniques such as by chromatography and/or crystallization.

It will be apparent to one skilled in the art that the compounds prepared in the above manner which are unsymmetrically substituted are usually obtained as a mixture of isomers. These isomers, i.e., the geometrical, stereo, and/or the optical isomers, can be separated at any desired stage of the process. In addition, the mixtures of isomers formed are readily subjected to the various processing steps with consequent production of a mixture of isomers of the final product which in turn may be readily separated by known means. The isomers prepared in the above manner when isolated in their pure form may differ in biological activity.

The 1, 2 or 3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene piperidine compounds and especially 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine are especially useful because of the fact that they possess appetite stimulant activity as measured in standard laboratory animals.

In the following illustrative preparations and examples, the isolation procedures are modified depending on product properties in accordance with principles well known to any skilled chemist.

Preparations Showing Use of 1-Alkyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidines and 1, 2 and 3-carboxyderivatives as intermediates in preparation of 10-oxo or 10-oxy compounds Preparation 1

1-Methyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine hydrochloride, 50 g. (0.146 mole) is stirred while warming with 100 ml. of 20% NaOH solution and 200 ml. of benzene until all of the salt is converted to the base and base dissolved in the benzene layer. The benzene layer containing the product is separated, washed, dried and evaporated under reduced pressure leaving the free base as a residue, which is dissolved in 500 ml. of ether. Dry hydrogen bromide gas is bubbled into the ether solution slowly with rapid stirring until no more precipitate is formed. This salt is collected and dried in a vacuum oven at 60°C. for 24 hours to give 1-methyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine hydrobromide, m.p. 257°-258°C.

PREPARATION 2 1-Methyl-4-(10,11-dibromo-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine Hydrobromide

1-Methyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine hydrobromide, 18.40 g. (0.05 mole) is dissolved with warming in 750 ml. of glacial acetic acid. This solution is cooled to room temperature and 8.0 g., 2.6 ml., (0.05 mole) of bromine dissolved in 75 ml. of glacial acetic acid is added dropwise with stirring. After completion of the addition the mixture is stirred overnight. The crystals are collected, washed with a small amount of cold glacial acetic acid, then with dry ether, and then dried for 2 hours in a vacuum oven at 70°C. to give 1-methyl-4-(10,11-dibromo-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)piperidine hydrobromide. Recrystallization from acetonitrile gives an analytical sample, m.p. 185°-186°C.

Anal. calcd. for C₂₁ H₂₁ NBr₂.HBr: C, 47.75; H, 4.20; N, 2.65. Found: C, 47.80; H, 4.21; N, 2.61.

PREPARATION 3

The procedure of Preparation 2 is repeated with appropriate modification of the isolation procedure using a stoichiometrically equivalent amount of each of the following correspondingly substituted 1-methyl-4-(5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidines having the following structure: ##SPC6##

in which one or more of the hydrogens of the benzene rings is substituted by an X or X' substituent as defined in the following table with resultant production of the corresponding 10,11-dibromo compound:

    ______________________________________                                                    X              X'                                                   ______________________________________                                         Compound 1, 1-Carboxy     H                                                    Compound 2, 3-Carboxy     H                                                    Compound 3, 2-Carboxy     H                                                    ______________________________________                                    

PREPARATION 4

The procedure of Preparation 3 is repeated with appropriate modification of the isolation procedure using a compound in which the N-methyl-piperidine substituent is replaced in each and every instance by each of the following substituents:

1. 1,2-dimethyl-piperidine

2. 1,2-diethyl-piperidine

3. 1,3-dimethyl-piperidine

4. 1,2,2-trimethyl-piperidine

5. 1,2,5-trimethyl-piperidine

6. 1,2,6-trimethyl-piperidine

7. 1-ethyl-2-methyl-piperidine

8. 1,2-diethyl-piperidine

9. 1-ethyl-3-methyl-piperidine

10. 1-ethyl-2,2-dimethyl-piperidine

11. 1-ethyl-2,5-dimethyl-piperidine

12. 1-ethyl-2,6-dimethyl-piperidine

PREPARATION 5 1-Methyl-4-(10-bromo-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine

To 600 ml. of a 0.40 M (0.24 mole) solution of potassium t-butoxide in t-butanol is added 42.1 g. (0.079 mole) of 1-methyl-4-(10,11-dibromo-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine hydrobromide and the mixture stirred vigorously under anhydrous conditions for 6 hours at room temperature. The reaction mixture is poured into 2 l. of water and extracted 3 times with 100 ml. each of benzene. The combined benzene extracts are dried over anhydrous MgSO₄, filtered, the MgSO₄ washed with benzene, and the benzene solution evaporated to dryness on a rotary evaporator. There remains 27.9 g. of crystalline product. This product is recrystallized by dissolving in 750 ml. of boiling hexane, filtered hot, the volume reduced to 200 ml. by boiling off hexane, seeding and allowing to crystallize. The crystals are collected and dried in a vacuum oven at 60°C. overnight to give 1-methyl-4-(10-bromo-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, m.p. 127°-129°C. Three more recrystallizations from hexane given an analytical sample with m.p. 130°-131°C.

Anal. calcd. for C₂₁ H₂₀ BrN: C, 68.85; H, 5.69; N, 3.82; Br, 21.82. Found: C, 68.78; H, 5.45; N, 3.79; Br, 21.94.

PREPARATION 6

The procedure of Preparation 5 is repeated with appropriate modification of the isolation procedure using as starting materials each of the products obtained in accordance with the procedure of Preparations 3 and 4, respectively, to produce the corresponding mono-bromo 1, 2 or 3-carboxydibenzocycloheptene compound.

PREPARATION 7 1-Methyl-4-(10-[1-piperidyl]-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine

1-Methyl-4-(10-bromo-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, 2.87 g. (0.0079 mole), 50 ml. of a 0.4M solution of potassium t-butoxide in t-butanol, and 20 ml. of dry piperidine is stirred and refluxed under anhydrous conditions for 6 hours. The reaction mixture is cooled and partitioned between 350 ml. of benzene and 50 ml. of water. The benzene layer is then extracted 5 more times with 50 ml. each of water. The benzene layer is then dried over anhydrous MgSO₄, filtered, and the benzene evaporated. This gives a single spot on t.l.c. and is used directly in the next step.

The product is crystallized from acetonitrilemethanol mixture. A sample sublimed for analysis has a m.p. of 71.5°-78°C.

Anal. calcd. for C₂₆ H₃₀ N₂ : C, 84.28; H, 8.16; N, 7.56. Found: C, 83.85; H, 8.14; N, 7.50.

PREPARATION 8

The procedure of Preparation 7 is repeated with appropriate modification of the isolation procedure using as starting materials each of the products obtained according to Preparation 6 with resultant production of the corresponding 1, 2 or 3-carboxy-10 and/or 11-(1-piperidyl)-5H-dibenzo[a,d]cycloheptene compound.

PREPARATION 9 1-Methyl-4-(10,11-dihydro-10-oxo-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine

1-Methyl-4-(10-[1-piperidyl]-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, 2.4 g., is refluxed for 4 hours with 100 ml. of 10% HCl in water and 50 ml. of methanol. The methanol is evaporated and the remaining oil and water is made basic with solid NaHCO₃ until no more CO₂ is evolved. It is then extracted three times with 50 ml. each of toluene, combined extracts dried over MgSO₄, filtered and the toluene evaporated on a rotary evaporator leaving a residual product which crystallizes on standing. Three recrystallizations of this product from hexane give 1-methyl-4-(10,11-dihydro-10-oxo-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, m.p. 142°-143°C.

Anal. calcd. for C₂₁ H₂₁ NO: C, 83.13; H, 6.98; N, 4.62. Found: C, 82.96; H, 6.80; N, 4.72.

PREPARATION 10

The procedure of Preparation 9 is repeated with appropriate modification of the isolation procedure using as the starting materials each of the products obtained in accordance with Preparation 8 with resultant production of the corresponding 1, 2 or 3-carboxy-10,11-dihydro-10 and 11-oxo-dibenzo[a,d]cycloheptene compound.

EXAMPLE 1 1-Methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine Hydrochloride

1-Methyl-4-(3-cyano-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine (16.5 g., 0.053 mole) is refluxed in 6 N HCl for 38 hours and cooled. The product is collected, washed with 30 ml. of cold 1 N HCl, then washed with acetonitrile, to give after drying 9.65 g. of 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine hydrochloride, m.p. 282°-289°C. (dec.). Recrystallization from dilute HCl and isopropanol mixture gives 6.2 g. of analytically pure product, m.p. 295°-300°C. (dec.). An additional 7.2 g. of product, m.p. 298°-300°C., is obtained by reworking the mother liquors.

Calcd. for C₂₂ H₂₁ NO₂ : C, 71.83; H, 6.03; N, 3.81. Found: C, 71.44; H, 6.24; N, 3.65.

EXAMPLE 2 1-Methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine Hydrochloride Semihydrate Step A. 3-cyano-5H-dibenzo[a,d]cyclohepten-5-one

3-Bromo-5H-dibenzo[a,d]cyclohepten-5-one (11.4 g., 0.04 mole), cuprous cyanide (7.17 g., 0.08 mole), 10 ml. of DMF and 100 ml. of freshly distilled quinoline are stirred under a slow stream of nitrogen and heated in an oil bath at 220°C. for 18 hours. The mixture is cooled and poured into 450 ml. of ether. The precipitate is filtered and the ether filtrate containing product is set aside. The remaining product is washed from the copper salts with chloroform. The solvent from the ether solution is removed in vacuo and taken up in 500 ml. of hot hexane and allowed to crystallize. This product is dissolved in chloroform and combined with the above chloroform solution. This solution is extracted three times with dilute HCl followed by saturated solution of NaHCO₃, dried over anhydrous MgSO₄, filtered and the solvent evaporated in vacuo to give 7.87 g. of 3-cyano-5H-dibenzo[a,d]cyclohepten-5-one, m.p. 176°-177°C. Recrystallization from acetonitrile gives 7.19 g., m.p. 176°-178°C. An analytical sample recrystallized from absolute ethanol melted at 179.3°-179.8°.

Calc. for C₁₆ H₉ NO: C, 83.10; H, 3.92; N, 6.06. Found: C, 82.87; H, 4.23; N, 6.10.

Step B. 3-Cyano-5-(1-methyl-4-piperidyl)-5H-dibenzo[a,d]cyclohepten-5-ol

3-Cyano-5H-dibenzo[a,d]cyclohepten-5-one (7.19 g., 0.031 mole) is dissolved in 250 ml. of distilled dry tetrahydrofuran. To this is added a solution of 1-methyl-4-piperidyl magnesium chloride (0.42 molar) until F1-silica thin layer chromatograph developed with 15% ethanol in toluene shows the starting ketone to be consumed (119 ml.). The reaction mixture is then cooled in an ice-water bath and 24 ml. of distilled water is added dropwise. The magnesium salts are filtered and washed with hot chloroform. The solvent is removed from the combined THF and chloroform solutions. The residue is taken up in chloroform and extracted with 5% HCl. The aqueous layer is made basic with dilute aqueous sodium hydroxide and extracted with ether. The ether extract is dried over anhydrous MgSO₄, filtered, and the solvent removed in vacuo. The residue is chromatographed on silica gel made basic with chloroform saturated with ammonia and water and eluted with chloroform saturated with ammonia and water. The fractions containing the product are combined and the solvent removed. The residue is taken up in chloroform, washed with dilute sodium hydroxide solution, dried over anhydrous MgSO₄, filtered, and the solvent evaporated. The residue is triturated with warm acetonitrile and cooled to give 4.95 g. of 3-cyano-5-(1-methyl-4-piperidyl)-5H-dibenzo[a,d]cyclohepten-5-ol, m.p. 219°-221°C.

Calc. for C₂₂ H₂₂ N₂ O: C, 79.97; H, 6.71, N, 8.48. Found: C, 79.86; H, 6.94; N, 8.60.

Step C. 1-Methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidine)-piperidine Hydrochloride Semihydrate

3-Cyano-5-(1-methyl-4-piperidyl)-5H-dibenzo[a,d]cyclohepten-5-ol (1.65 g., 5 mmoles) is dissolved and refluxed in 50 ml. of 6 N HCl for 48 hours. The reaction is cooled and the solvent removed in vacuo. The residue is triturated with 50 ml. of isopropanol and filtered from ammonium chloride. The solution of product is reduced in volume to 30 ml. and small amounts of ether added and the solution of the product filtered from the precipitate. This solution is then diluted with ether to a volume of approximately 400 ml. The product is collected and dried in a vacuum oven overnight to give 1.10 g. of 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine hydrochloride, m.p. 190°-200°C. Recrystallization from boiling acetonitrile yields 0.56 g., m.p. 291°-293°C. (D) isolated as the semihydrate.

Calcd. for C₂₂ H₂₁ NO₂.HCl.1/2 H₂ O: C, 70.11; H, 6.15; N, 3.71; Cl, 9.41. Found: C, 70.22; H, 6.05; N, 3.76; Cl, 9.56.

EXAMPLE 3 REPRESENTATIVE PHARMACEUTICAL COMPOSITION PREPARATION

A typical tablet containing 1 mg. of 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine per tablet is prepared by mixing together with the active ingredient calcium phosphate dibasic, lactose and starch in the amounts shown in the table below. After these ingredients are thoroughly mixed, the appropriate amount of magnesium stearate is added and the dry mixture blended for an additional 3 minutes. This mixture is then compressed into tablets weighing approximately 124 mgs. each.

    ______________________________________                                         TABLET FORMULA                                                                 Ingredient          Mgs. per tablet                                            ______________________________________                                         1-methyl-4-(3-carboxy-5H-                                                      dibenzo[a,d]cyclohepten-5-                                                     ylidene)-piperidine 1                                                          Calcium phosphate dibasic                                                                          52                                                         Lactose             60                                                         Starch              10                                                         Magnesium stearate  1                                                          TOTAL               124       mg.                                              ______________________________________                                    

Capsules for oral use each containing 1 mg. of 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-yl-idene)-piperidine are prepared by blending 1 gram of 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine with 287 grams of lactose, U.S.P. 4.1 grams of magnesium stearate. This is then used to fill 1000 capsules each containing 1 mg. of 1-methyl-4-(3-carboxy-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine.

EXAMPLE 4 Preparation of Starting Material of Example 1: 1-methyl-4-(3-cyano-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine

1-Methyl-4-(3-bromo-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine (3.33 g., 9 mmoles) and cuprous cyanide (1.25 g., 14 mmoles) are refluxed in 20 ml. of dry dimethylformamide for 6 hours. The reaction is then poured while hot into 50 ml. of water. To this is added 50 ml. of a saturated solution of sodium cyanide and 25 ml. each of benzene and ether. After vigorous shaking the organic layer is separated and the aqueous layer extracted with ether. The combined organic extracts are dried over anhydrous magnesium sulfate, filtered, and the solvent evaporated in vacuo to leave an oil which when crystallized from acetonitrile gives 1.5 g. of 1-methyl-4-(3-cyano-5H-dibenzo[a,d]cyclohepten-5-ylidene)-piperidine, m.p. 140°-142°C. The sample is further purified by chromatography on 140 g. of silica gel made basic with chloroform saturated with ammonia and water, eluting with chloroform saturated with ammonia and water, then crystallized from ethyl acetate to give an analytical sample, m.p. 141°- 146°C.

Calcd. for C₂₂ H₂₀ N₂ : C, 84.58; H, 6.45; N, 8.97. Found: C, 84.59; H, 6.56; N, 8.89. 

What is claimed is:
 1. A 5H-dibenzo[a,d]cycloheptene compound of the formula ##SPC7##wherein the carboxyl group is in the 1-, 2-, or 3-position; R₂ is hydrogen, a lower alkyl or a lower alkenyl substituent; R is methyl or ethyl and replaces one or more of the hydrogens in positions 2, 3, 5 or 6 of the piperidine ring, provided that only one of positions 3 and 5 is substituted in any one compound; n is 0, 1 or 2; and X' is selected from hydrogen and an alkyl group having up to 6 carbon atoms.
 2. A compound according to claim 1 of the formula ##SPC8## 